Numerical embankment breach modelling including seepage flow effects

The multi-physical processes during embankment breaching due to overtopping are complex and known to depend upon seepage flow through the embankment. A numerical breach model for progressive embankment breaching is proposed, taking the seepage flow into account including its influence on slope stability due to apparent cohesion effects. Overtopping and embankment surface erosion are computed using finite-volume methods applied to the 2D shallow-water and the Exner equations. The seepage flow is modelled using a Lattice–Boltzmann approach solving the 3D Richards' equation. The modules are executed in a coupled manner with dynamically adapted boundary conditions. The breach side wall failures are considered using a geometrical approach based on critical failure angles. This approach is enhanced to account for apparent cohesion effects by dynamically adapting the critical failure angles as a function of the water saturation in a heuristic way, as a major enhancement compared to previous approaches. The model is successfully applied to a laboratory experiment of a small-scale spatial embankment breach.